In the process of drilling and completion of a well conduit, production of a well conduit, servicing of a well conduit or abandonment of a well conduit, many different tools have been developed to provide a seal in the annulus between one conduit and another such as between the well bore and casing, and well production tubing or some similar work conduit. Some of these tools provide a means of securing the seal means from upward or downward movement induced by pressure differentials acting upon the seal and/or loads imposed by movement of the tubing string. In as many such tools it is required that the tool provide within its structure a means of releasing both the seal means and anchoring means for retrieval of the tool with minimal effort.
It is known in prior art to provide a retrievable well packer. These devices may be run and set in the desired location within the well bore by attachment to a tubing string or wireline. When a tubing string is used, the packer may be actuated to form a seal and secure the packer to the casing by using hydraulic pressure in the tubing, hydrostatic pressure in the well, or a combination of both, and also mechanically by the weight of the tubing string or tension applied through use of a hoisting mechanism on the surface.
In the case where a packer is run to setting depth on a wireline, the setting force required for establishment of the seal and securing the packer to the well casing is provided by a wireline setting tool and a releasing adapter.
Some packers and more specifically those designed to be run and set on wireline are of a free standing seal bore type or more commonly called retainer production packer in that they are capable of maintaining their seal and securing means against the well casing without the aid of the tubing string. A seal bore is incorporated by means of the internal bore of the packer for placement of a tubing mounted sealing assembly. The tubing mounted sealing assembly is capable of traveling upwardly and downwardly within the packer bore while maintaining the annular seal and also provides for retrieval of the tubing string and tubing seal assembly without recovery of the packer.
The retainer type production packer places a restriction within the well bore. To remove this restriction for unrestricted passage of equipment below the setting points of the retainer production packer requires the drilling up of the retainer production packer if it is the permanent type, or removal with a releasing tool, if it is of the retrievable type, which is run in the well on either a tubing string or wireline attached to the packer and then, through manipulation of the running-in means, the retainer production packer is released from its sealed and secured position and may then be recovered from the well.
In the past, the releasing means within the packer which allowed the retainer production packer to be released from its seal to the casing and from its secure position in relation to vertical movement within the well bore has tended to fail and release the tool from its secured position under high pressure differential loads.
An example of such a retrievable retainer production that is operated by a wireline setting tool is shown in U.S. Pat. No. 3,678,998 issued to D. W. Cockrell et al on July 24, 1972. This patent disclosure is incorporated herein by this specific reference thereto. The invention is distinctively different from this patent in its structure and operation and has several advantages over the above patent.
One advantage is that it is common to use the packer of the invention and other such retrievable packers such as shown in the above identified patent in combination with a seal assembly at the bottom of the production tubing. If, when a seal assembly is used in connection with the Cockrell et al patent, the seal assembly seizes in the seal bore of the packer, you cannot recover the packer as with the instant invention. Another advantage is of the instant invention is that it permits placement of temporary plugging devices and restrictive connected devices on the bottom of the packer body and still maintains the ability to release the packer. The design of the releasing mechanism is such that it allows several additional benefits to the overall improvement of this type of downhole tool. These improvements allow for a larger inside diameter seal bore, an improvement in the pressure holding capability of such tools, and isolation of the releasing mechanism from produced well fluids. Also, the releasing mechanism is not subjected to tension forces tending to over-stress the releasable lock when subjected to high differential pressure loads.
An object of the patent is to provide a well packer or engaging apparatus which can be released from its set, sealed, and secured position in a well bore when the packer bore is intentionally or inadvertently restricted by placement of seal assemblies, temporary plugging devices, or any such device that would prevent passage through the packer body. Another object of the invention is to provide a releasing mechanism that is not subjected to tension load failure when high fluid pressures are placed to the internal bore of the packer with the bottom of the packer plugged or when high fluid pressure are subjected to the bottom of the packer which tends to move the packer up the well bore in relation to its secure position. Another objective is to isolate the releasing mechanism from the produced fluid flow path to protect the releasing mechanism from corrosion and produced undissolved solid materials that could negate its desired operation.